Network Security Services (NSS) is a set of libraries designed to support the cross-platform development of security-enabled client and server applications. Netscape Portable Runtime (NSPR) provides platform independence for non-GUI operating system facilities.
This update adds support for the TLS Fallback Signaling Cipher Suite Value (TLS_FALLBACK_SCSV), which can be used to prevent protocol downgrade attacks against applications which re-connect using a lower SSL/TLS protocol version when the initial connection indicating the highest supported protocol version fails.
This can prevent a forceful downgrade of the communication to SSL 3.0. The SSL 3.0 protocol was found to be vulnerable to the padding oracle attack when using block cipher suites in cipher block chaining (CBC) mode. This issue is identified as CVE-2014-3566, and also known under the alias POODLE. This SSL 3.0 protocol flaw will not be addressed in a future update; it is recommended that users configure their applications to require at least TLS protocol version 1.0 for secure communication.
For additional information about this flaw, see the Knowledgebase article at https://access.redhat.com/articles/1232123
The nss, nss-util, and nss-softokn packages have been upgraded to upstream version 184.108.40.206, which provides a number of bug fixes and enhancements over the previous version, and adds the support for Mozilla Firefox 31.3. (BZ#1158159, BZ#1165003, BZ#1165525)
Users of nss, nss-util, and nss-softokn are advised to upgrade to these updated packages, which contain a backported patch to mitigate the CVE-2014-3566 issue, fix these bugs, and add these enhancements. After installing this update, applications using NSS or NSPR must be restarted for this update to take effect.